U.S. patent number 8,336,967 [Application Number 12/067,830] was granted by the patent office on 2012-12-25 for method of tapering bristles for toothbrushes, and toothbrush having bristles manufactured by said method.
Invention is credited to Sung-Hwan Kwon, Sung-Wook Kwon, Young-Jun Kwon.
United States Patent |
8,336,967 |
Kwon , et al. |
December 25, 2012 |
Method of tapering bristles for toothbrushes, and toothbrush having
bristles manufactured by said method
Abstract
The present invention provides a method of tapering bristles for
toothbrushes and a toothbrush having bristles manufactured using
the method. One method disclosed in the present invention includes
setting bristles made of polyester in a head insert, and fastening
the bristles to the head insert by thermally welding portions of
the bristles, protruding from a back surface of the head insert, to
the head insert. The method further includes coupling the head
insert to a toothbrush body and tapering ends of the bristles by
immersing the bristles in a chemical. The bristles can be securely
set in the toothbrush body without an anchor. Furthermore,
polyester bristles, which could not be set in toothbrushes having
variously shaped setting rows due to excessively high stiffness,
can be set in these types of toothbrush by the toothbrush
manufacturing method of the present invention.
Inventors: |
Kwon; Young-Jun (Gyunggi-do,
KR), Kwon; Sung-Wook (Seoul, KR), Kwon;
Sung-Hwan (Seoul, KR) |
Family
ID: |
37943031 |
Appl.
No.: |
12/067,830 |
Filed: |
October 16, 2006 |
PCT
Filed: |
October 16, 2006 |
PCT No.: |
PCT/KR2006/004164 |
371(c)(1),(2),(4) Date: |
April 16, 2008 |
PCT
Pub. No.: |
WO2007/043848 |
PCT
Pub. Date: |
April 19, 2007 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20080224529 A1 |
Sep 18, 2008 |
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Foreign Application Priority Data
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Oct 14, 2005 [KR] |
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10-2005-0096824 |
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Current U.S.
Class: |
300/21 |
Current CPC
Class: |
A46D
1/05 (20130101); A46B 3/06 (20130101); A46B
2200/1066 (20130101); A46D 3/045 (20130101); A46B
9/04 (20130101) |
Current International
Class: |
A46D
3/00 (20060101) |
Field of
Search: |
;15/167.1,DIG.5
;300/21 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Chin; Randall
Attorney, Agent or Firm: Egbert Law Offices, PLLC
Claims
We claim:
1. A method of manufacturing a toothbrush, the method comprising:
setting bristles in a head insert such that one end of the bristles
protrude from a back surface of the head insert, said bristles
being of a polyester material; thermally welding said one end of
the bristles to said head insert; coupling said head insert to a
toothbrush body; and tapering an opposite end of the bristles after
the step of setting by immersing the bristles in a chemical such
that an end point at an opposite end of the bristles has a
thickness of between 0.01 millimeters and 0.07 millimeters, said
opposite end of the bristles having a tapered portion extending
therefrom, said tapered portion having a length of between 3
millimeters and 7 millimeters.
2. A method of manufacturing a toothbrush, the method comprising:
setting bristles in a head insert such that one end of the bristles
protrude from a back surface of the head insert, said bristles
being of a polyester material; thermally welding said one end of
the bristles to said head insert; placing said head insert into a
cavity of a mold; injecting resin into the cavity so as to form a
toothbrush body integral with said head insert; and tapering an
opposite end of the bristles after the step of setting by immersing
the bristles in a chemical such that an end point at an opposite
end of the bristles has a thickness of between 0.01 millimeters and
0.07 millimeters, said opposite end of the bristles having a
tapered portion extending therefrom, said tapered portion having a
length of between 3 millimeters and 7 millimeters.
3. The method of claim 2, further comprising: placing a pressure
relief unit on said back surface of said head insert prior to the
step of injection.
4. A method of manufacturing a toothbrush, the method comprising:
setting bristles in a head insert such that one end of the bristles
protrude from a back surface of the head insert, said bristles
being of a polyester material; thermally welding said one end of
the bristles to said head insert; tapering an opposite end of the
bristles after the step of setting by immersing the bristles in a
chemical such that an end point at an opposite end of the bristles
has a thickness of between 0.01 millimeters and 0.07 millimeters,
said opposite end of the bristles having a tapered portion
extending therefrom, said tapered portion having a length between 3
millimeters and 7 millimeters; and coupling said head insert a
toothbrush body.
5. A method of manufacturing a toothbrush comprising: setting
bristles in a mold; placing a pressure relief unit on back surface
of a head insert; injecting resin into a cavity of sail mold so as
to form a toothbrush body such that the bristles are coupled to the
toothbrush body; and tapering ends of the bristles after the step
of setting by immersing the bristles in a chemical such that end
points of the ends of the bristles have a thickness of between 0.01
millimeters to 0.07 millimeters, said bristles having a tapered
portions extending from said end points, each of said tapered
portions having a length of between 3 millimeters to 7
millimeters.
6. The method of claim 5, said bristles comprising polyester
bristles and non-polyester synthetic bristles combined separately
and together in said mold.
7. The method of claim 5, further comprising: physically grinding
the ends of the bristles.
8. The method of claim 5, said end points having differing
thicknesses.
Description
CROSS-REFERENCE TO RELATED U.S. APPLICATIONS
Not Applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT
Not Applicable.
REFERENCE TO AN APPENDIX SUBMITTED ON COMPACT DISC
Not Applicable.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates, in general, to methods of tapering
bristles for toothbrushes and toothbrushes having bristles
manufactured using the methods. More particularly, the invention
related to a method of tapering bristles for anchor-less
toothbrushes and a anchor-less toothbrush which has bristles
manufactured using the method.
2. Description of Related Art Including Information Disclosed Under
37 CFR 1.97 and 37 CFR 1.98.
In conventional methods of manufacturing toothbrushes having
tapered bristles, a bundle of bristles, each having an end point
from 0.16 to 0.2 mm in diameter, is cut to a predetermined length.
Thereafter, the end points of the bristles are hydrolyzed by an
alkali chemical or strong acid chemical, thus being tapered.
Subsequently, the bristles are washed in water and dried. The
bristles are thereafter folded in half and set in holes, formed in
a head part of a toothbrush body, using anchors.
Recently, toothbrushes have followed trends, so that various
bristle setting patterns have been required. Furthermore, according
to an increase in the size of a bundle of bristles, it has been
difficult to set bristles using a conventional bristle setting
machine and to fasten bristles with an anchor.
Three methods of manufacturing an anchor-less toothbrush are as
follows.
First, as a method used by Coronet Co., Ltd. of Germany, bristles
are set in a mold and, thereafter, resin is injected into the mold,
thus integrating the bristles with a toothbrush body.
Second, as a method used the Oral-B company of U.S.A, bristles are
set in a mold brush plate and, thereafter, the head insert having
bristles is placed in a mold. Subsequently, resin is injected into
the mold, thus fastening the bristles to a toothbrush body.
Third, as a method used the Boucherie company of Belgium which uses
a bundle of bristles having a predetermined length, unlike other
companies which use a spooled filament as a bristle. Bristles are
set in a head insert made of plastic and, thereafter, the head
insert is seated into a head insert seat formed in a head part of a
toothbrush body. Subsequently, the head insert is bonded to the
toothbrush body by ultrasonic waves.
The above-mentioned methods can reliably fasten bristles to a
toothbrush body without anchor. However, the equipment is very
expensive, and productivity is relatively low. Moreover, because a
mold, a bristle setting machine and an injection molding machine
are integrated together, it is very difficult to change the setting
pattern of bristles.
However, toothbrushes manufactured by the above-mentioned methods
can realize various bristle setting patterns. Thus, the appearance
is superior. As well, the bristle setting pattern can freely be
designed to match the tooth structure of every race. Therefore,
toothbrushes manufactured by the above-mentioned methods have been
popular among consumers.
In the toothbrushes manufactured by the above-mentioned methods, to
realize various bristle setting patterns, the volume of a bundle of
bristles must become large. As a result, it is impossible to taper
bristles using a conventional physical grinding method. It is well
known that if bristles are tapered, flexibility is increased so
that the gums of a user are protected from injury while brushing
the teeth, and penetration ability of the bristles is increased,
thus enhancing tooth brushing efficiency.
In conventional anchor-less toothbrushes, because a spooled
filament is typically used as bristles, it is difficult to taper
bristles. Therefore, instead of a method of tapering bristles,
bristles made of relatively flexible nylon, for example, nylon 6,
10, and nylon 6, 12 are used, thus overcoming the above-mentioned
problems. However, a nylon bristle has insufficient durability and
water resistance, compared with a polyester bristle. Also, because
the penetration ability of bristles, which are not tapered, is
poor, tooth brushing efficiency is reduced. Furthermore, bristles
made of polyester cannot be used in such a toothbrush due to
excessively high stiffness.
Due to these reasons, a tapering process is required even when
manufacturing toothbrushes having various setting patterns. There
are bristle tapering methods as follow. As described above, there
is a method wherein a bundle of bristles is cut to a predetermined
length and, thereafter, the ends of the bristles are hydrolyzed by
an alkali chemical or strong acid chemical, thus being tapered.
Subsequently, the bristles are washed in water and dried.
Thereafter, the dried bristles are folded in half and set in a
toothbrush body using anchors. There is a second method wherein
bristles are tapered by a physical method such as a grinding method
after a bristle setting process is conducted. There is a third
method wherein bristles are partially tapered by the first method
and then additionally machined by the second method.
However the second method is problematic because the length of
tapered portions of the bristles is relatively short, such that the
bristles are not sufficiently flexible. On the other hand, the
third method has the advantages of solving the problem of the
method the second method and reducing the manufacturing costs. This
method was proposed in Korean Patent No. 261658 which was filed by
the inventor of the present invention.
In addition, as proposed in Japanese Patent No. 3022762, there is a
method wherein bristles are are immersed in an alkali chemical unit
just before the cores of the bristles are dissolved, thus tapering
ends of the bristles, after bristles are fastened to a toothbrush
body using anchors made of metal, particularly, aluminum.
However, this method is problematic because the alkali chemical
penetrates to the anchors due to a capillary phenomenon during the
bristle immersion process. Thus, the anchors may be undesirably
dissolved. If the anchors are dissolved, the set bristles may be
removed from the toothbrush body. Furthermore, in the case of a
mass production process, because hydrogen gas is generated when
aluminum anchors react with alkali, there is the probability of the
explosion of gas due to the heat in a reaction flask. Even if the
material of the anchor is changed into brass, which has been
popular, dissolution may occur because zinc, added to increase the
stiffness of brass, react with alkali chemical.
Due to these reasons, a product manufactured by this method has
been not commercialized. In consideration of economical efficiency,
only products, which are manufactured by the method in which
bristles are cut to predetermined lengths, both ends of the
bristles are tapered using a chemical, and the bristles are folded
in half and set in toothbrush bodies using anchors, have been
commercialized.
Furthermore, in a toothbrush manufactured by this method, the
thickness of an end point of each bristle is 50% or more than the
thickness of the end point of the bristle before chemical-treating
the bristle, and the tapered portion of the bristle is only about 3
mm. Therefore, penetration ability into gaps between teeth and
flexibility are limited. To solve these problems, in Korean Patent
No. 261658 which was filed by the inventor of the present
invention, bristles are immersed in a chemical until just before
the length of the bristles is reduced, thus being partially
tapered. Thereafter, the bristles are set in a toothbrush body, and
the bristles are ground by a grinder such that the diameter of an
end of each bristle ranges from 0.04 mm to 0.08 mm. This method can
solve problems of dissolution of an anchor and of a lack of
penetration ability and flexibility.
However, the bristle tapering techniques, which are disclosed in
the above-mentioned prior art, such as the conventional art
proposed by the inventor of the present invention, have common
problems. For example, the techniques cannot be applied to a
toothbrush having variously shaped setting rows.
In an effort to overcome the above-mentioned problems, another
technique was proposed in Korean Patent No. 3073200 which was filed
by the inventor of the present invention. Unlike prior art using
double-ended needle-shaped bristles, both ends of which are
tapered, this technique uses single-ended needle-shaped bristles,
only one end of which is tapered. The length of each single-ended
needle-shaped bristle is half the length of the double-ended
needle-shaped bristle. To manufacture a toothbrush, single-ended
needle-shaped bristles are received in a receiving unit and are
then inserted into a head insert, in which through holes having
predetermined shapes are formed, by an insert rod of a pushing
plate. Thereafter, portions of bristles protruding from a back
surface of the head insert are thermally welded, thus fastening the
bristles to the head insert. Subsequently, the head insert having
the bristles is bonded to a toothbrush body. Alternatively, after
the head insert is placed in a mold, an injection molding process
is conducted, thus integrating the head insert with the toothbrush
body.
In this technique, the bristles are reliably fastened to the
toothbrush body without an anchor. Furthermore, because only one
end of each bristle is tapered, the defective proportion is
markedly low, thereby the manufacturing costs are also reduced. As
well, this technique can manufacture toothbrushes having variously
shaped setting rows.
However, there are problems as follows. As a first problem, in this
technique, a bundle of bristles is cut to a length ranging from 15
to 20 mm and chemical-treated such that the length of tapered
portions of bristles ranges from 4 to 8 mm and the thickness of end
points of the bristles ranges from 0.01 to 0.03 mm. Thereafter, the
bristles are tied with an elastic band after washing in water and
drying them. Subsequently, the bristles are set in a bristle supply
machine before a bristle setting process is conducted. At this
time, some bristles may be broken due to their short lengths while
removing the elastic band. Thus, the loss of bristles is increased.
As a second problem, because the end point of the bristles have low
thickness ranging from 0.01 to 0.03 mm, when the bristles are set
in through holes of the head insert by the insert rod, the ends of
the bristles may be undesirably bent. As a result, heights of the
set bristles are uneven. As a third problem, the surface area of
tapered bristles differs from the surface area of bristles which
are not tapered. Accordingly, even for a skilled worker, much labor
is required when setting the bristles in the toothbrush body.
BRIEF SUMMARY OF THE INVENTION
Accordingly, the present invention has been made keeping in mind
the above problems occurring in the prior art, and an object of the
present invention is to provide a toothbrush which has variously
shaped setting rows and tapered bristles. Another object of the
present invention is to provide a toothbrush which is manufactured
by a simple manufacturing process. A further object of the present
invention is to provide a toothbrush which has superior water
resistance ability and durability, wherein bristles easily
penetrate into gaps between teeth. Yet another object of the
present invention is to provide a toothbrush manufacturing method
which is able to reduce the defective proportion.
Technical Solution
In one aspect, the present invention provides a toothbrush
manufacturing method including: setting bristles made of polyester
into holes formed in a mold; injecting resin into the mold and
forming a toothbrush body such that the bristles are integrated
with the toothbrush body; and tapering ends of the bristles by
immersing the bristles in a chemical.
In another aspect, the present invention provides a toothbrush
manufacturing method, including: setting bristles made of polyester
into a head insert; fastening the bristles to the head insert by
thermally welding portions of the bristles, protruding from a back
surface of the head insert, to the head insert; coupling the head
insert, to which the bristles are fastened, to a toothbrush body;
and tapering ends of the bristles by immersing the bristles in a
chemical.
In a further aspect, the present invention provides a toothbrush
manufacturing method, including: setting bristles made of polyester
into a head insert; fastening the bristles to the head insert by
thermally welding portions of the bristles, protruding from a back
surface of the head insert, to the head insert; tapering ends of
the bristles by immersing the bristles in a chemical; and coupling
the head insert, to which the bristles are fastened, to a
toothbrush body.
In yet another aspect, the present invention provides a toothbrush,
including: bristles made of polyester and having end points from
0.01 to 0.03 mm in thickness and tapered parts from 4.0 to 10.0 mm
in length. The bristles are set in a head part of a toothbrush
without anchor. In the present invention, polyester means
polyethylene terephthalate (PET), polybutylene terephthalate (PBT)
or polytrimethylene terephthalate (PTT).
Advantageous Effects
In the present invention, the bristles can be securely set in a
toothbrush body without an anchor. Furthermore, polyester bristles,
which could not be set in toothbrushes having variously shaped
setting rows due to excessively high stiffness, can be set in these
types of toothbrush using the present invention. Particularly, the
present invention can efficiently manufacture a toothbrush having
variously shaped setting rows without expensive equipment.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
FIG. 1 is a partial schematic view showing a conventional
toothbrush body to which bristles are fastened by anchor.
FIG. 2 is a schematic view showing a toothbrush body having
variously shaped setting rows.
FIG. 3 is a perspective view of a head insert to be used in the
present invention.
FIG. 4 is a sectional view showing a process of setting bristles
into a head insert, according to the present invention.
FIG. 5 is a sectional view showing the bristles fastened to the
head insert by thermally welding parts of the bristles protruding
from a back surface of the head insert, according to the present
invention;
FIG. 6 is a perspective view showing the head insert in which
bristles are set.
FIG. 7 is a perspective view of a holding jig to be used in the
present invention.
FIG. 8 is a view showing a process of fastening the head insert
having bristles to a toothbrush body according to the present
invention.
FIG. 9 is a schematic view showing the head insert, to which
bristles are fastened, placed in a mold according to the present
invention.
FIG. 10 is a sectional view showing a process of integrating
bristles, set in a mold, with a toothbrush body.
FIG. 11 is a view showing a pressure relief unit placed on the back
surface of the head insert according to the present invention.
DESCRIPTION OF THE ELEMENTS IN THE DRAWINGS
1: toothbrush body 10: insert head 20: holding jig h: hole S:
receiving unit u: head insert seat
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with
reference to the attached drawings.
FIG. 1 is a partial view showing a conventional toothbrush body to
which bristles are fastened by anchors. In this case, bristles are
set in holes (h) formed in a head part of the toothbrush body. In
FIG. 1, the diameter of a bundle of bristles ranges from 1.6 to 4.0
mm. In the case larger than the above-mentioned range, it is
impossible to fasten bristles to the toothbrush body using an
anchor.
FIG. 2 is a schematic view showing a toothbrush body which has
variously shaped setting rows and is used for a toothbrush to be
manufactured by a method in which bristles are thermally welded to
a head insert 10 without an anchor, or in which the bristles are
set in a mold. In this method, because a bundle of bristles is
fastened to the toothbrush without an anchor, the size and shape
are not limited to predetermined ranges. As such, because the size
and shape are not limited to predetermined ranges, variously shaped
setting holes (h) can be formed in the toothbrush.
The method of the present invention can be applied both to a method
in which bristles are set in the head insert 10 and, thereafter, a
head insert 10 is coupled to a toothbrush body 1, and to a method
in which bristles are set in a mold and, thereafter, resin is
injected into the mold to form a toothbrush body 1 so that the
bristles are integrated with the toothbrush body 1.
The former method will be explained herein below.
FIG. 3 shows a head insert 10 to be used in the present invention.
The head insert 10 has variously shaped setting holes (h) therein.
Bristles are set in the setting holes (h). The end points of the
bristles to be set may have the same thickness. Alternatively, the
end points of the bristles may have different thicknesses. In the
case of the bristles having end points different in thickness,
there is an advantage of extension of the lifespan of a
toothbrush.
Furthermore, polyester bristles along with bristles made of
different material, for example, along with nylon bristles, may be
set in the head insert 10. In the case that bristles made of
different materials are combined together, when the different
bristles are immersed in a chemical to taper the bristles, some
bristles may not be hydrolyzed. From this, the cleaning ability of
the toothbrush may be appropriately adjusted. In detail, polyester
bristles are hydrolyzed when being immersed in a chemical, thus
having flexibility and penetration ability. On the other hand,
bristles made of other material are not hydrolyzed, thus having
high stiffness and cleaning ability. If such characteristic is
appropriately adjusted, a toothbrush having desired properties can
be obtained.
FIG. 4 is a sectional view showing a process of setting bristles
into the head insert 10. FIG. 5 is a sectional view showing the
bristles fastened to the head insert 10 by thermally welding parts
of the bristles protruding from a back surface of the head insert.
The bristles are set in the head insert 10 such that portions of
the bristles protrude from the back surface of the head insert by 1
to 3 mm. The portions of the bristles protruding from the back
surface of the insert head are fastened to the head insert 10 by
thermal welding. The head insert 10 to which the bristles are
fastened is shown in FIG. 6.
The bristles fastened to the head insert 10 are tapered by
immersing end portions of the bristles in an acid or alkali
chemical. Thereafter, the head insert 10 having the bristles is
fastened to the toothbrush 1. As a preferable immersion method, as
shown in FIG. 7, a holding jig 20 which holds the head insert 10 is
used. The holding jig 20 has a receiving hole which has a size
large enough to receive all bristles therein, but smaller than the
head insert. The bristles are received in the receiving hole, and
the head insert 10 is held by the holding jig 20. When using the
holding jig 20 to hold the head insert 10, it is easy to immerse
the bristles to desired lengths.
Here, the bristles may be completely tapered in the above-mentioned
immersion process. Alternatively, after the bristles are partially
tapered using the immersion process, an additional physical
tapering process such as a grinding process may be executed.
Regardless of a bristle tapering method, it is preferable that the
bristles be tapered such that the thickness of the end points
ranges from 0.01 to 0.07 mm and the length of the tapered portions
ranges from 3 to 7 mm.
FIG. 8 is a view showing a process of fastening the head insert 10,
to which bristles are fastened, to a toothbrush body 1. The head
insert 10 is fastened to the toothbrush body 1 by inserting the
head insert 10 into a head insert seat (u) formed in the toothbrush
body 1.
This method has advantages as follows. Because only the relatively
small head insert 10, to which bristles are fastened, is involved
in a bristle tapering process, a large number of bristles is
treated at one time, compared with a method in which bristles are
directly set in a mold and, thereafter, the bristles are integrated
with a toothbrush body by injecting resin into the mold.
Furthermore, even when bristles are washed in water after
conducting a process of immersing in a chemical, there is an
advantage thanks to the small size. Also, because the back surface
of the head insert 10 is exposed to the outside, the time required
to wash the head insert 10 in water is reduced. In addition, when a
defect occurs, only the head insert 10 is scrapped. The entire
toothbrush is not scrapped. Consequently, the loss of products is
reduced. Moreover, during the bristle tapering process, the
toothbrush body is prevented from being contaminated. However, this
method cannot be applied to a product to be manufactured by a
method in which an entire toothbrush body 1 is simultaneously
formed without a separate head part thereof.
As another method of fastening the head insert 10 to a toothbrush
body 1, there is a method in which the head insert 10 having
bristles is placed in the mold and, thereafter, resin is injected
into the mold. In this method, the head insert can be integrated
with the toothbrush body without a separate bonding process. As
required, a pressure relief unit (r) having a thin plate shape may
be layered on the back surface of the head insert before the resin
injection process (see, FIG. 11). The pressure relief unit (r)
prevents resin from flowing out along the bristles due to injection
pressure. FIG. 9 is a view showing the head insert 10, to which
bristles are fastened, placed in the mold.
Unlike the above-mentioned toothbrush manufacturing methods, a
method, in which bristles are directly set in a mold and,
thereafter, a toothbrush body is formed by injecting resin into the
mold so that the bristles are integrated with the toothbrush body,
is as follows.
After bristles are set in the mold in a shape shown in FIG. 10, as
disclosed in Korean Patent Laid-open Publication No. 2001-00341454,
parts of the bristles protruding into a cavity of the mold are
thermally welded so that bristle setting holes of the mold are
sealed. Thereafter, resin is injected into the cavity of the mold.
At this time, the pressure of the cavity of the mold is sensed to
prevent resin from leaking out along the bristles through the
bristle setting holes of the mold. If the pressure of the cavity is
greater than a preset value, the resin injection is temporarily
stopped. When the pressure of the cavity is returned to the normal
value, the resin injection resumes. By such a method, the bristles
set in the mold are integrated with the toothbrush body.
The bristles of the toothbrush, which is manufactured using the
above-mentioned method, are immersed in a chemical and are thus
tapered in the same manner as that described for the toothbrush
manufacturing method using the head insert 10.
In the toothbrush manufacturing methods described above, as
required, bristles may be intentionally unevenly set in a
toothbrush body such that the lengths of exposed portions of the
bristles differ from each other within a range from 1 to 10 mm.
Several examples of methods of manufacturing toothbrushes are as
follows.
Example 1
Bristles, which have end points of 0.19 mm in thickness and are
made of PTT, are set in a mold mounted to an AFT CNC machine which
was produced by Boucherie Company of Belgium. Thereafter, portions
of the bristles protruding into a cavity of the mold are thermally
welded, and resin is injected into the cavity of the mold, thus
manufacturing a toothbrush such that the bristles are integrated
with a toothbrush body.
The manufactured toothbrush is fastened to a holding jig similar to
that shown in FIG. 7 and is then immersed for 17 minutes in a
reaction flask in which 35% sodium hydroxide solution is maintained
at 120.degree. C. Subsequently, the toothbrush is washed in water,
neutralized and dried so that the toothbrush having tapered
bristles is obtained. As a result, the thicknesses of the end
points of the bristles range from 0.01 to 0.02 mm. The lengths of
the tapered portions of the bristles range from 5 to 7 mm.
Example 2
A head insert, to which anti-bacterial bristles, which have end
points of 0.18 mm in thickness, are made of PBT, and are
manufactured by Kanebo Company of Japan, is manufactured, similar
to the head insert of FIG. 6, using the machine used in the first
example. This head insert is treated through the same bristle
tapering process as that of the first example. As a result, the
thicknesses of the end points of the bristles range from 0.01 to
0.03 mm. The lengths of the tapered portions of the bristles range
from 4 to 6 mm.
The manufactured head insert having bristles is seated into a
bristle seat formed in a head part of a toothbrush body and is then
bonded to the head part using ultrasonic waves, thus a toothbrush
is obtained.
Example 3
A spooled filament, which has end points of 0.203 mm (8 mils) in
thickness and is made of PBT, is continuously supplied to a
weld-type toothbrush manufacturing machine which was made by
Coronet Co., Ltd. of Germany, thus manufacturing a toothbrush in
which bristles are set.
The manufactured toothbrush is fastened to a holding jig similar to
that shown in FIG. 7 and is then immersed for 10 minutes in a
reaction flask in which 95% sulfuric acid solution is maintained at
135.degree. C., thus tapering the bristles. Subsequently, the
toothbrush is washed in water, neutralized and dried. As a result,
the thicknesses of the end points of the bristles range from 0.01
to 0.04 mm. The lengths of the tapered portions of the bristles
range from 4 to 6 mm.
Example 4
Three kinds of bristles, which have end points of 0.152 mm, 0.178
mm and 0.203 mm in thickness and made of PBT and polyester
elastomer mixed in a weight ratio of 7:3, are set in a head insert,
made of plastic, by the machine used in the first example. Here,
the bristles having end points of 0.152 mm in thickness are set in
a central portion of the head insert. The bristles having end
points of 0.178 mm in thickness are set in an intermediate portion
of the head part. The bristles having end points of 0.203 mm in
thickness are set in an edge portion of the head insert.
The manufactured head insert is fastened to the holding jig of FIG.
7 and is then immersed for 10 minutes in a reaction flask in which
98% sulfuric acid solution is maintained at 115.degree. C.
Subsequently, the head insert is washed in water, neutralized and
dried, so that a toothbrush having tapered bristles is obtained. As
a result, the thicknesses of the end points of the bristles range
from 0.01 to 0.04 mm. The lengths of the tapered portions of the
bristles range from 5 to 7 mm.
Example 5
Anti-bacterial bristles of Kanebo Company of Japan, which have end
points of 0.18 mm in thickness and are made of PBT, and nylon
bristles, which have end points of 0.20 mm in thickness, are
combined in a ratio of 1:1. The time to immerse the bristles in a
chemical is changed to 12 minutes. Other conditions are the same as
those of the second example. In the above-mentioned conditions, a
toothbrush is manufactured through the same process as that of the
second example.
As a result, the thicknesses of the end points of the PBT bristles
range from 0.03 to 0.05 mm, and the thicknesses of the end points
of the nylon bristles are 0.20 mm.
Thereafter, the bristles are ground for 10 seconds using a drum
grinder having protrusions for 10 seconds. As a result, bristles,
which have end points from 0.01 to 0.02 mm in thickness and tapered
parts from 3 to 5 mm in length, and bristles, which have end points
from 0.10 to 0.15 mm in thickness and tapered parts from 1 to 2 mm
in length, are combined together.
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